Method for producing asphalt



'fe'rred in; the roofingindustry;

sitivity test.

Patented Aug. 17; 1943 orat on l .ME'riroDFoR rnonocmensrriarr panels n.can, Los Angeus, an Harold W.

i Ritchey;'Long Beach, Calif., assignorsto Union Oil Company ofCalifornia, Les a corporation of California Angeles, Qalifi,

. Z No Drawing. Application we is, less. a

Serial No. 279,492 4 a (oi. lea-22y Y '6 Claims.

This invention relates to an improved coating or airblown asphaltandto aprocess for manufacturing the same. i v V It is well recognized in theart-oi manufacturingair-blown i. e. oxidized or coating type asphalts,that these products may. be prepared by blowing the charging stock, suchas asphalt residua producedfrom asphaltmontaining crude oils, with .airor other oxygen-containing gases at-an .elevated temperature. Theproduct resulting from .this'operation will possess, desirable 'lowtemperature susceptibilities; a higher melting point for a givenpenetration as compared with un'oxidized asphalts and. a moderatelyhigh,

ductility.) Thistype of asphalt is generally pre- 1 In recentyears,attention has been-focused on the light-promoted oxidation of asphaltand as a resultof manyroof failures,,the Minnesota Mining andManufacturing Company has investigated the effectof-light andjmoistureon asphalt and has devised what is now known as the photosen- They.found that under certaindegrees of exposure to light, all asphalts forma thin jsurface coating of oxidized materials, and that by "immersingtheexposed asphalt in warm water,

the degree'of oxidation can be strikingly shown by a color change. jSufficiently oxidized surfaces take on a yellow, paint-like appearance,which has been'termed rust. The length of exposure .necessary todevelopthis rust is ,takenasan indication of the degree of photosensitivityof'the asphalt.

, The work of the above Minnesota company was mainly concerned with theloss of adhesiveness of the asphaltfor roofing granules in the case ofroll roofing or asphalt shinglesiin' which the surfaces are coated withmineral granules which may transmit a certain amount "of light. Sur-'face oxidation of thelasphalt in the presence of light was assumed bythem to correspond to a lo'ss'of binding powervfor the granules.Asphalts which thus show a high degree of photosensitlvity according tothe photosensitivity test are regarded as unsuitable 'for'use with theirgranules.

"However, an aspect of more serious conse- 'quence to the-roofing tradein general is the fact that in the light reaction certain acidicwatersoluble substances are formed "which; if not washed completely citby-rain, tend to concentrate in dew puddles and leave yellow stains,especially in hot, moist climates. This is a frequent' source ofcomplaint in the case of mopped roofs or built-up roofing. It should benoted that this form of stain, whichmayz-il'so effect the color ofgranules inshingle-coatedroofs, has

nothing whatever; to dowith the-staining due to oil exudation and infact, is most frequently encountered with certain asphalts which showlow stain numbers by the Barber test, which measures the tendency of anasphalt to exude oil.

;'Ihe fact that the water-solubleportion of these oxidation productsis'acidic often results rather extensive corrosion of down spouts,galvanized roof gutters, etc.

Also it will be noted that-the photosensitivity phenomenon has nonecessary connection with the fundamental weathering behavior of the'asphalt. Inv fact, some of the asphalts which ohave the longestWeather-Ometer life are the most photosensitive and conversely, some ofthe poorest asphalts from a Weather-Ometer standjfpointare the bestfroma photosensitivity standpoint; i. e: are the, least photosensitive.Thus,

some asphalts which are otherwise considered to ,be good: .asphalts andhave a long .Weather'- Qm'eter lifehav thedisadvantage ofbeingveryphotosensitive. By Weather-Ometer life is meant "thelife of an'asphaltas measured by thetest developed by Dr. stricter fog the U. 3. Bureau ofStandards. i

' [Thus, it is an object of invention to produce non-photosensitiveasphalts from photosensitive asphalts. f 1 a We have found thatione ofthe properties of an asphalt mostinfiuencing the photosensitivity test,i. e resulting'in a high photosensitivity, is

the'presence. ofja relatively light oil in'the asphalt.

Our experimentation relating to fractionation of the photosensitiveasphalts has shown that the reactive constituents in photosensitiveasphalts are confined tothe oils. and are"'concentrated chiefly in therelatively light and medium lubricating oils. "By vacuum topping, ithas. been found' possible .to prepare heavy oils from suchphotosensitive crude oils as Santa Maria Valley (California) crude oilwhich are relatively, inert to light. Thus, by a suitable'fractionationprocedur'e, it is possible to produce from such .photosensitiveasphalts, a flux, which, upon air blowing to the desiredcharacteristics, is considerably improved in respect tophotosensitivity.

' ,We havealso found it possible to producea flux from a photosensitiveasphalt, which, upon "oxidation with air, results inthe productionof arelatively non-photosensitive coating asphalt by subjecting the asphaltor topped asphaltic re- "siduum to extraction with solvents which arecapable oiprecipitatingthe asphaltenes and also resins'contained in theasphalt and dissolving the V oil' fractions therein; Wejhave found thatthe solvent precipitatedasphaltenes and resins are relatively inert withrespect to light. By subject,-

' ing the light sensitive solvent soluble fraction to distillation toremove light oils, we have found that the residue consisting of a heavyoil is relatively stable to light, this stability toward lightincreasing with the boiling range of the heaviest overhead cutrerncved.By blending the heavy oil bottoms with the precipitated asphaltenes andresin in the desired proportions, a composite d asphalt which is stabletowards light may be produced and which, if desired, may beair-lblown'to produce an oxidized asphalt which is stable towards light.

The precipitation of the asphaltenes and also resins may be accomplishedby extracting the 2 11 with solvents such as the liquefied normallygaseous hydrocarbons, such as ethane, -prqpane, butane and isobutane ormixtures thereof. The separation with these solvents may be effected bysimply mixing the asphalt with the solvent e at normal temperatures-ormore -elevated temperature er about 103 F; under pressure Sui-iiclient-to maintain the solventin the liquidstate at the temperature'employed; For example; "in

the case-of propane, approximatelythree tosix volumes of propane -may be-mix'e dwith the asphalt residuurn at a temperature of about 100 -F.-ands pressure ofabout "l'lfi-pounds persquare inch. This mixture isallowed to-remain-in *a quieseent'state until the precipitatedasphaltenes and resins havesettledto the bottom'ofthecontainer in-which-the admixture'wasefiected. ,The clear supernatant solution of oiland-propane substantially free from or containing relatively smallamountsof 'resins is decanted frorn the s. settled-asphaltenes andresins and ,is subjected to' distlllation 'to remove the propanewhich-may be recovered by compression'and cooling and re-v turned foryfurthertr'eatment of re iduum, The propane-free oil may thenbeslubjectedto distillation and fra'ctionation in order to separate-thelight;oils contained therein which carry the phctosensii'nvematerials; -The bottoms ,are 'then'blendedin the desired'proportionwith'the previously precipitated asphaltenes .and resins,

,e, tlculariy .tlie resins of low 7 molecular 'weie'ht,

the'production of air-blown asphalts-which have a relatively lowWeather-()mter life; These 7 e i maybe removed bysubjectinetheprwanprecip tated asphaltene-iresin mixture to extraction with ,a solventcapable of wdissolving the resins; at least the resins of, lowmoleculanweight, but not substantial amounts @of .the asphaltene atzthetemperatureemployed. .For thispurpose, relatively j'heavier. solventsmay be used such as petroleum (ether. Asian examplathreeorfour .3

volumes ,of petroleum ether may -b.e.mixed with the propane precipitated,a'sphaltene-resin mixture at a temperature otabout ,175 ,F. .and themixtureallowedto settle. Ihesolution ofpetrolellmsetber andfresinsisnextdecantedfrom the settled asphaltenes. The latter is then subjiected..to distillation ttoaremove .any -,petroleum ether mntainea therein..The asphaltenes may in' he blowing stock are generally responslbleior'u:

distillation in order to distill the oil fractions tracted oil in suchproportions as to produce a flux which may be air-blown to the desiredmelting point-penetration characteristics.

Experimentation has also shown that materials is asphalt which areresponsible for high light sensitivity are aromatic ,or unsaturated innature since they may be removed by extraction of the light or mediumlubricating oils with a sective solvent capable of separating the oilinto '1 a relatively paraflinic fraction and a relativelynon-iparaflinicior aromatic or naphthenic oil fraction. In order toproduce the relatively nonphotosensitive asphalt, the asphalt or toppedasphaltlclcrude-oil -may be subjected to vacuum from the asphaltenes orthe oils may be sepa- 11 ated from the asphaltenes by the'aforementionedprecipitation with solvents such as pro- ,Dfine. {The oil is thenextracted by known extraction methods with a selective solvent, suchasphenol, liquid sulfur dioxide, -furfural andthe 'll-l 'e, to-separatethe oil into -a-raffinate phase and an extract phase. The raflinatephase is next stripped of solvent and the rafilin'ateithus "produced is*blended with the aforementioned distillationbottoms, i. e. asphaltenes,or solvent precipitateda-sphaltenes in such desired proportions'astoprodueeaeompositedasphaltwhich may'be used as composited 'or-whichmay be subjected to mild ormore severe oxidation "with air or etheroxygen-containing gas. 'If desired, the rafiinateoil may besubjected-todistillation to remove light oils before being ,composited with --theasphaltenes. I'heselight oils, however, are

lthenbe blendediwiththe bottoms-resulting-from the distillation of thepreviousl :Pmpitlifi @8- generally not sensitive to light since thelight sensitive materialshavgbeen removed by the.extraction-prqcess-andremainin the extractphase.

.In order to :still'iurther decrease the photoj sensitivity :or theabove produced asphalts, small amounts, ie 025 to 10% by weight ofcertaln "inhibitors :ofphoto-oxidation may be mixed with theasphalt.=For"this purpose, we have found a large n mber of. ubs ances which maybe added to'the asphalt to reduce DhQt'OEQXl-dQ-tiflll. Compounds thatare characterized by .pbla character, 1 one hydrocarbon cha.insterminating in a polar group. .such .as oxygenated smu'p nitro grou s,su phonic mups, halo or aromatic nuclei, have been found to beparticularly suitablelas inhihitorslof photoeoxidation. Ihe'nigherstraight chainlfatty acidssuch as lauric, tridecoic, myristic,pentadec0ic,rpa1- mitic, margaric, stearic, nondecoic, arachidic,eicosoicor eicosanic, behenic, tricosoic, lignoceric or carnaubic,pentaco'soic, cerotic, ,hexacosoie, carboceric, montanic, acids, andalso-the alcohols derived from the above higher straight chain fattyacids such as laury1,.ol.eyl,,stearyl, etc., al- 6 .1015 .havevbeenfound to be particu r y acti inhibitors of photosoxidation. Also, thehigher straight chainiolefinic acids iundecylinic, myris- .tolenic,ipalmitolin c, .o1eic; petroselie, eruci brassidic, nervonicandlikeolefinic acids-maybe used as inhibitors of photo-. oxidation.Likewise, the alcoholsrderived from these olefinickaeidsare ,goodinhibitors of photo-oxidation. Montan-wax,

carnauba wax, hydrogenatedfishoiliacids, acidulated cocoanut oil acids,acidulated shortening oiLaeids, cottonseed oil acids, etc,,;may-a1so;beused. Parafiin wax which-hasbeenpxidimgl gt t vely :low temperatures:under conditionsrfai s ng'fatty acid ratherthan estolide orhydmxyacid-formation has alsobeen ioundt be an :6- aieetive -i-nhibit0r.

1:5 iIhe renewi :sii m tted :as specific sexamples of our invention.These,- however, are

not tobe considered as limiting but merely as illustrative of theinvention.

. Emme m A Santa Maria Valley crude oil was topped with steam to producean asphalt residue having a viscosity of 120 seconds furol at 210F. Thisresidue was then mixed with four" volumes of propane at a temperature of100 F. under a pressure of 175 lbs.per square inch. The mixture wasallowed to remain in a quiescent state at this temperature and pressurein order to permit the precipitated-asphalt to settle below the solutionof oil and propane. The latter was decanted from the settled asphalt andthe two separated fractions were distilled to remove propanetherefrom.Approximately 53% by weight of propane soluble oil was obtained having aviscosity of 80 seconds Saybolt Universal at 210 F. and low flash pointof 250 F. (Cleveland Open Cup). A portion of this oil was then distilledunder vacuum to remove as overhead consisting of light and mediumlubricating oils. The bottoms representing 60% of the extracted oil hada viscosity of 150 seconds Saybolt Universal at 210 F.

These bottoms were then blended with a vacu urn distilled asphaltproduced from the same Santa Maria Valley crude oil having a meltingpoint of 125 F. and a penetration of 40 at 77 F. The blend was effectedin the proportions of 60% by weight of the asphalt and 40% by weight ofthe above bottoms. had a viscosity of 378 seconds furol at 210.F. and aflash point of 530 F. (Cleveland Open Cup);

The blend of asphalt and oil was then oxidized with air'at a temperatureof 100- 150 F. for i hours, using 5,cubic feet of air per barrel ofcharge per minute. The oxidized. charge showed a melting point of 217F., penetrations of 14 at 32 F., 18 at 77 F. and-33 at 115 F., aductility of 4.0 at 77 11, a flash point of 520 F. (Cleveland Open Cup)and a Barber stain number of 2.0.

An aluminum panel was coated with this asphalt to a thickness of 0.025inch and the coated panel was then exposed to the radiation of a 1500watt lamp at a distance of 6 inches from the lamp. The panel was exposedfor 28 hours and was then immersed in warm waterat 140 F. resulting inthe formation of a light rust which remained upon drying the panel. Norust was 7 formed on similar panels exposed less than 28 hours.

In order to compare the photosensitivity of the above asphalt with asimilar asphalt of 217 F. melting point but which had not been subjectedto the process of the above invention, another portion of topped SantaMaria Valley crude oil Example 2 Another portion of the propaneextracted oil bottoms having a viscosity of 450 seconds SayboltUniversal at 210 F. of the above example was blendedwitli the propaneprecipitated asphalt of the above example in the proportions of byweight of the precipitated asphalt and 60% The composited blend Analuminum panel by weight of the oil-bottoms. The blend showed aviscosity of 500 seconds furol at 210 F. and. a flash'point of 560(Cleveland Open Cup).

This blend was oxidized with air as previously describedto produce anair-blown asphalt having a melting point of 220 K, penetrations of 15 at32 F., 19 at 77 F. and 31 at 115 F., a ductility of 4.2 and a flashpoint of 530 F. (Cleveland Open Cup). 'When apanel .coated with thisasphalt was subjected to the above photosensitivity test, there was noevidence ofrust formation atYthe end of thirty-two hours exposure tothe. lamp.

' Example} The remaining portion of the propaneextracted oil ofExample 1. having a viscosityof'80 seconds Saybolt Universal at 210 F.and a flash point of 250 F. was extracted five times at 100 F. with amixture consisting of 90% phenol and 10% water, using two volumes ofselective solvent to one of the oil on each extraction. The raffinateproduced by the five extractions had a viscosity of 172 seconds SayboltUniversal at 210 F. and a viscosity gravity constant of 0.836.

The precipitated asphalt of Example 1 which contained resins .wasextracted with 350 volume percent of petroleum ether at a temperature ofabout 175 F. to effect solution of the resins in the petroleum ether.The mixture was allowed to settle and the supernatant solution of resinsand petroleum ether was decanted away from the settled asphaltenes. Thelatter was then stripped of the petroleum ether and was blended with thepreviously described raflinate in the proportions of 7 by weight of therafiinate to 40% by weight of the asphaltenes to produce a blendedasphalt having a melting point of 220 F. and a penetration of 40 at 77F. This blend was then tested, as above, for photosensitivity and showedno rust formation at the end of thirty-two hours.

It will be observed that for determining the melting point andpenetration, the following methods outlined by the American Society ofTesting materials were used:

Melting point (ball and ring method) 13-36-26 Penetration D-5-25 Theterm viscosity gravity constant hasbeen defined by Hill and Coates inthe Journal of Industrial and Engineering Chemistry, of 1928, vol. 20,page 641. This constant is an indication of the parafiinicity ornaphthenicity of oil, a high value representing a high degree ofnaphthenicity, while a low value indicates a relatively greaterparafiinicity.

The foregoing description of our invention is not to be construed aslimiting but only as illustrative of the invention as many variationsmay be made within the scope of the following claims.

We claim:

1. A method for producing relatively non-photosensitive asphalt fromrelatively photosensitive asphalt which comprises mixing said asphaltwith a solvent capable of dissolving oil but incapable of dissolvingasphaltenes at the temperature employed, separating a solution of oil insaid solvent from said asphaltenes, subjecting said separated oil toextraction with a solvent capable of dissolving relativelynon-p'araflinic oil fractions but not relatively paraffinic oilfractions, separating said relatively non-parafiinic oil fractions fromsaid relatively paraffinic fractions, distilling said relativelyparaflinic fractions to remove light and medium lubricating oils andcornmingling the remaining heavier paraffinic oil fractions with saidsepamtetl'aspihaltenmsito produce:arelativelynom photosensitive asphalt,s H

2. A method accnrrlixxg. m claim 1 in which saidrsolventicapablezofdissolving oil but incapable of zdissolvingaaspheltenes at thetemperatureemployed'oomprises a liquefied normallygaseous hy- A methodaccording to .claim 1 .in which said :solven't capable *ofdissolving-oil but incapable u'f admolving asphaltenes at the temperaiureremployedicomprises propane.

A. :A method according toclaim V1 in which said solvent capable ofdissolving relatively n0nparafflnic oil fractions 'biit'not relativelyparaffinic :oil :fmctions'icomprises phenol.

5 A,.method accezdingzto'fcla'imi l in which said solvent capable ofdissolving oil but; incepable of dissolving asphaltenes at thetemperafinic oil fractions comprises phenol.

DONALD E. CARR. HAROLD W. RITCHEY.

